Kosmiese ruisabsorpsie te SANAE gedurende 1964

Abstract

Cosmic noise absorption measured by a 30 Mc/s Riometer at the South African Antarctic base, SANAE, was used to deter mine the temporal and latitudinal variation in ionospheric absorption . It was found that absorption at SANAE showed the same temporal and latitudinal variations as stations in the northern hemisphere. variations were found at SANAE, The following 1) A seasonal variation in the number of absorption events, with a minimum in December. 2) A seasonal variation in the aver age absorption with a minimum in August. 3) A daily variation in absorption during the southern winter and spring months, but not during the southern summer. Basler's curve for the latitudinal variation in absorption ll) was used to determine the position of the southern aurora belt in relation to SANAE from the riometer data. A good correlation was found with Feldstein's experimental auroral belt lg) and a theoretical auroral belt by Hultqvist 19 ). The interpretation here was that the Southern

Radiation Anomaly has no effect on the position of the southern auroral belt. Individual absorption events of types F and S were analyzed and correlated with aurora and geomagnetic disturbances. The results seemed to confirm a similar study by Berkey and Parthasarathy 15 ) for the northern hemisphere. In several cases a time difference was found between the maximum absorption and the maximum of a magnetic bay in the H- component . When the maximum absorption succeeded the maximum of the magnetic bay, it was interpreted as a result of the decay of the ringcurrent. When the maximum absorption preceded the maximum of the magnetic bay, it was ascribed to an influx of energetic particles preceding the particles that fed the ringcurrent.